import express from 'express';
import { spawn } from 'child_process';
import path from 'path';
import os from 'os';
import { promises as fs } from 'fs';
import crypto from 'crypto';
import { apiKeysDb, githubTokensDb } from '../database/db.js';
import { addProjectManually } from '../projects.js';
import { queryClaudeSDK } from '../claude-sdk.js';
import { spawnCursor } from '../cursor-cli.js';

const router = express.Router();

// Middleware to validate API key for external requests
const validateExternalApiKey = (req, res, next) => {
  const apiKey = req.headers['x-api-key'] || req.query.apiKey;

  if (!apiKey) {
    return res.status(401).json({ error: 'API key required' });
  }

  const user = apiKeysDb.validateApiKey(apiKey);

  if (!user) {
    return res.status(401).json({ error: 'Invalid or inactive API key' });
  }

  req.user = user;
  next();
};

/**
 * Get the remote URL of a git repository
 * @param {string} repoPath - Path to the git repository
 * @returns {Promise<string>} - Remote URL of the repository
 */
async function getGitRemoteUrl(repoPath) {
  return new Promise((resolve, reject) => {
    const gitProcess = spawn('git', ['config', '--get', 'remote.origin.url'], {
      cwd: repoPath,
      stdio: ['pipe', 'pipe', 'pipe']
    });

    let stdout = '';
    let stderr = '';

    gitProcess.stdout.on('data', (data) => {
      stdout += data.toString();
    });

    gitProcess.stderr.on('data', (data) => {
      stderr += data.toString();
    });

    gitProcess.on('close', (code) => {
      if (code === 0) {
        resolve(stdout.trim());
      } else {
        reject(new Error(`Failed to get git remote: ${stderr}`));
      }
    });

    gitProcess.on('error', (error) => {
      reject(new Error(`Failed to execute git: ${error.message}`));
    });
  });
}

/**
 * Normalize GitHub URLs for comparison
 * @param {string} url - GitHub URL
 * @returns {string} - Normalized URL
 */
function normalizeGitHubUrl(url) {
  // Remove .git suffix
  let normalized = url.replace(/\.git$/, '');
  // Convert SSH to HTTPS format for comparison
  normalized = normalized.replace(/^git@github\.com:/, 'https://github.com/');
  // Remove trailing slash
  normalized = normalized.replace(/\/$/, '');
  return normalized.toLowerCase();
}

/**
 * Clone a GitHub repository to a directory
 * @param {string} githubUrl - GitHub repository URL
 * @param {string} githubToken - Optional GitHub token for private repos
 * @param {string} projectPath - Path for cloning the repository
 * @returns {Promise<string>} - Path to the cloned repository
 */
async function cloneGitHubRepo(githubUrl, githubToken = null, projectPath) {
  return new Promise(async (resolve, reject) => {
    try {
      // Validate GitHub URL
      if (!githubUrl || !githubUrl.includes('github.com')) {
        throw new Error('Invalid GitHub URL');
      }

      const cloneDir = path.resolve(projectPath);

      // Check if directory already exists
      try {
        await fs.access(cloneDir);
        // Directory exists - check if it's a git repo with the same URL
        try {
          const existingUrl = await getGitRemoteUrl(cloneDir);
          const normalizedExisting = normalizeGitHubUrl(existingUrl);
          const normalizedRequested = normalizeGitHubUrl(githubUrl);

          if (normalizedExisting === normalizedRequested) {
            console.log('✅ Repository already exists at path with correct URL');
            return resolve(cloneDir);
          } else {
            throw new Error(`Directory ${cloneDir} already exists with a different repository (${existingUrl}). Expected: ${githubUrl}`);
          }
        } catch (gitError) {
          throw new Error(`Directory ${cloneDir} already exists but is not a valid git repository or git command failed`);
        }
      } catch (accessError) {
        // Directory doesn't exist - proceed with clone
      }

      // Ensure parent directory exists
      await fs.mkdir(path.dirname(cloneDir), { recursive: true });

      // Prepare the git clone URL with authentication if token is provided
      let cloneUrl = githubUrl;
      if (githubToken) {
        // Convert HTTPS URL to authenticated URL
        // Example: https://github.com/user/repo -> https://token@github.com/user/repo
        cloneUrl = githubUrl.replace('https://github.com', `https://${githubToken}@github.com`);
      }

      console.log('🔄 Cloning repository:', githubUrl);
      console.log('📁 Destination:', cloneDir);

      // Execute git clone
      const gitProcess = spawn('git', ['clone', '--depth', '1', cloneUrl, cloneDir], {
        stdio: ['pipe', 'pipe', 'pipe']
      });

      let stdout = '';
      let stderr = '';

      gitProcess.stdout.on('data', (data) => {
        stdout += data.toString();
      });

      gitProcess.stderr.on('data', (data) => {
        stderr += data.toString();
        console.log('Git stderr:', data.toString());
      });

      gitProcess.on('close', (code) => {
        if (code === 0) {
          console.log('✅ Repository cloned successfully');
          resolve(cloneDir);
        } else {
          console.error('❌ Git clone failed:', stderr);
          reject(new Error(`Git clone failed: ${stderr}`));
        }
      });

      gitProcess.on('error', (error) => {
        reject(new Error(`Failed to execute git: ${error.message}`));
      });
    } catch (error) {
      reject(error);
    }
  });
}

/**
 * Clean up a temporary project directory and its Claude session
 * @param {string} projectPath - Path to the project directory
 * @param {string} sessionId - Session ID to clean up
 */
async function cleanupProject(projectPath, sessionId = null) {
  try {
    // Only clean up projects in the external-projects directory
    if (!projectPath.includes('.claude/external-projects')) {
      console.warn('⚠️ Refusing to clean up non-external project:', projectPath);
      return;
    }

    console.log('🧹 Cleaning up project:', projectPath);
    await fs.rm(projectPath, { recursive: true, force: true });
    console.log('✅ Project cleaned up');

    // Also clean up the Claude session directory if sessionId provided
    if (sessionId) {
      try {
        const sessionPath = path.join(os.homedir(), '.claude', 'sessions', sessionId);
        console.log('🧹 Cleaning up session directory:', sessionPath);
        await fs.rm(sessionPath, { recursive: true, force: true });
        console.log('✅ Session directory cleaned up');
      } catch (error) {
        console.error('⚠️ Failed to clean up session directory:', error.message);
      }
    }
  } catch (error) {
    console.error('❌ Failed to clean up project:', error);
  }
}

/**
 * SSE Stream Writer - Adapts SDK/CLI output to Server-Sent Events
 */
class SSEStreamWriter {
  constructor(res) {
    this.res = res;
    this.sessionId = null;
  }

  send(data) {
    if (this.res.writableEnded) {
      return;
    }

    // Format as SSE
    this.res.write(`data: ${JSON.stringify(data)}\n\n`);
  }

  end() {
    if (!this.res.writableEnded) {
      this.res.write('data: {"type":"done"}\n\n');
      this.res.end();
    }
  }

  setSessionId(sessionId) {
    this.sessionId = sessionId;
  }

  getSessionId() {
    return this.sessionId;
  }
}

/**
 * Non-streaming response collector
 */
class ResponseCollector {
  constructor() {
    this.messages = [];
    this.sessionId = null;
  }

  send(data) {
    // Store ALL messages for now - we'll filter when returning
    this.messages.push(data);

    // Extract sessionId if present
    if (typeof data === 'string') {
      try {
        const parsed = JSON.parse(data);
        if (parsed.sessionId) {
          this.sessionId = parsed.sessionId;
        }
      } catch (e) {
        // Not JSON, ignore
      }
    } else if (data && data.sessionId) {
      this.sessionId = data.sessionId;
    }
  }

  end() {
    // Do nothing - we'll collect all messages
  }

  setSessionId(sessionId) {
    this.sessionId = sessionId;
  }

  getSessionId() {
    return this.sessionId;
  }

  getMessages() {
    return this.messages;
  }

  /**
   * Get filtered assistant messages only
   */
  getAssistantMessages() {
    const assistantMessages = [];

    for (const msg of this.messages) {
      // Skip initial status message
      if (msg && msg.type === 'status') {
        continue;
      }

      // Handle JSON strings
      if (typeof msg === 'string') {
        try {
          const parsed = JSON.parse(msg);
          // Only include claude-response messages with assistant type
          if (parsed.type === 'claude-response' && parsed.data && parsed.data.type === 'assistant') {
            assistantMessages.push(parsed.data);
          }
        } catch (e) {
          // Not JSON, skip
        }
      }
    }

    return assistantMessages;
  }

  /**
   * Calculate total tokens from all messages
   */
  getTotalTokens() {
    let totalInput = 0;
    let totalOutput = 0;
    let totalCacheRead = 0;
    let totalCacheCreation = 0;

    for (const msg of this.messages) {
      let data = msg;

      // Parse if string
      if (typeof msg === 'string') {
        try {
          data = JSON.parse(msg);
        } catch (e) {
          continue;
        }
      }

      // Extract usage from claude-response messages
      if (data && data.type === 'claude-response' && data.data) {
        const msgData = data.data;
        if (msgData.message && msgData.message.usage) {
          const usage = msgData.message.usage;
          totalInput += usage.input_tokens || 0;
          totalOutput += usage.output_tokens || 0;
          totalCacheRead += usage.cache_read_input_tokens || 0;
          totalCacheCreation += usage.cache_creation_input_tokens || 0;
        }
      }
    }

    return {
      inputTokens: totalInput,
      outputTokens: totalOutput,
      cacheReadTokens: totalCacheRead,
      cacheCreationTokens: totalCacheCreation,
      totalTokens: totalInput + totalOutput + totalCacheRead + totalCacheCreation
    };
  }
}

// ===============================
// External API Endpoint
// ===============================

/**
 * POST /api/agent
 *
 * Trigger an AI agent (Claude or Cursor) to work on a project
 *
 * Body:
 * - githubUrl: string (conditionally required) - GitHub repository URL to clone
 * - projectPath: string (conditionally required) - Path to existing project or where to clone
 * - message: string (required) - Message to send to the AI agent
 * - provider: string (optional) - 'claude' or 'cursor' (default: 'claude')
 * - stream: boolean (optional) - Whether to stream responses (default: true)
 * - model: string (optional) - Model to use (for Cursor)
 * - cleanup: boolean (optional) - Whether to cleanup project after completion (default: true)
 * - githubToken: string (optional) - GitHub token for private repos (overrides stored token)
 *
 * Note: Either githubUrl OR projectPath must be provided. If both are provided, githubUrl will be cloned to projectPath.
 */
router.post('/', validateExternalApiKey, async (req, res) => {
  const { githubUrl, projectPath, message, provider = 'claude', model, githubToken } = req.body;

  // Parse stream and cleanup as booleans (handle string "true"/"false" from curl)
  const stream = req.body.stream === undefined ? true : (req.body.stream === true || req.body.stream === 'true');
  const cleanup = req.body.cleanup === undefined ? true : (req.body.cleanup === true || req.body.cleanup === 'true');

  // Validate inputs
  if (!githubUrl && !projectPath) {
    return res.status(400).json({ error: 'Either githubUrl or projectPath is required' });
  }

  if (!message || !message.trim()) {
    return res.status(400).json({ error: 'message is required' });
  }

  if (!['claude', 'cursor'].includes(provider)) {
    return res.status(400).json({ error: 'provider must be "claude" or "cursor"' });
  }

  let finalProjectPath = null;
  let writer = null;

  try {
    // Determine the final project path
    if (githubUrl) {
      // Clone repository (to projectPath if provided, otherwise generate path)
      const tokenToUse = githubToken || githubTokensDb.getActiveGithubToken(req.user.id);

      let targetPath;
      if (projectPath) {
        targetPath = projectPath;
      } else {
        // Generate a unique path for cloning
        const repoHash = crypto.createHash('md5').update(githubUrl + Date.now()).digest('hex');
        targetPath = path.join(os.homedir(), '.claude', 'external-projects', repoHash);
      }

      finalProjectPath = await cloneGitHubRepo(githubUrl.trim(), tokenToUse, targetPath);
    } else {
      // Use existing project path
      finalProjectPath = path.resolve(projectPath);

      // Verify the path exists
      try {
        await fs.access(finalProjectPath);
      } catch (error) {
        throw new Error(`Project path does not exist: ${finalProjectPath}`);
      }
    }

    // Register the project (or use existing registration)
    let project;
    try {
      project = await addProjectManually(finalProjectPath);
      console.log('📦 Project registered:', project);
    } catch (error) {
      // If project already exists, that's fine - continue with the existing registration
      if (error.message && error.message.includes('Project already configured')) {
        console.log('📦 Using existing project registration for:', finalProjectPath);
        project = { path: finalProjectPath };
      } else {
        throw error;
      }
    }

    // Set up writer based on streaming mode
    if (stream) {
      // Set up SSE headers for streaming
      res.setHeader('Content-Type', 'text/event-stream');
      res.setHeader('Cache-Control', 'no-cache');
      res.setHeader('Connection', 'keep-alive');
      res.setHeader('X-Accel-Buffering', 'no'); // Disable nginx buffering

      writer = new SSEStreamWriter(res);

      // Send initial status
      writer.send({
        type: 'status',
        message: githubUrl ? 'Repository cloned and session started' : 'Session started',
        projectPath: finalProjectPath
      });
    } else {
      // Non-streaming mode: collect messages
      writer = new ResponseCollector();

      // Collect initial status message
      writer.send({
        type: 'status',
        message: githubUrl ? 'Repository cloned and session started' : 'Session started',
        projectPath: finalProjectPath
      });
    }

    // Start the appropriate session
    if (provider === 'claude') {
      console.log('🤖 Starting Claude SDK session');

      await queryClaudeSDK(message.trim(), {
        projectPath: finalProjectPath,
        cwd: finalProjectPath,
        sessionId: null, // New session
        permissionMode: 'bypassPermissions' // Bypass all permissions for API calls
      }, writer);

    } else if (provider === 'cursor') {
      console.log('🖱️ Starting Cursor CLI session');

      await spawnCursor(message.trim(), {
        projectPath: finalProjectPath,
        cwd: finalProjectPath,
        sessionId: null, // New session
        model: model || undefined,
        skipPermissions: true // Bypass permissions for Cursor
      }, writer);
    }

    // Handle response based on streaming mode
    if (stream) {
      // Streaming mode: end the SSE stream
      writer.end();
    } else {
      // Non-streaming mode: send filtered messages and token summary as JSON
      const assistantMessages = writer.getAssistantMessages();
      const tokenSummary = writer.getTotalTokens();

      res.json({
        success: true,
        sessionId: writer.getSessionId(),
        messages: assistantMessages,
        tokens: tokenSummary,
        projectPath: finalProjectPath
      });
    }

    // Clean up if requested
    if (cleanup && githubUrl) {
      // Only cleanup if we cloned a repo (not for existing project paths)
      const sessionIdForCleanup = writer.getSessionId();
      setTimeout(() => {
        cleanupProject(finalProjectPath, sessionIdForCleanup);
      }, 5000);
    }

  } catch (error) {
    console.error('❌ External session error:', error);

    // Clean up on error
    if (finalProjectPath && cleanup && githubUrl) {
      const sessionIdForCleanup = writer ? writer.getSessionId() : null;
      cleanupProject(finalProjectPath, sessionIdForCleanup);
    }

    if (stream) {
      // For streaming, send error event and stop
      if (!writer) {
        // Set up SSE headers if not already done
        res.setHeader('Content-Type', 'text/event-stream');
        res.setHeader('Cache-Control', 'no-cache');
        res.setHeader('Connection', 'keep-alive');
        res.setHeader('X-Accel-Buffering', 'no');
        writer = new SSEStreamWriter(res);
      }

      if (!res.writableEnded) {
        writer.send({
          type: 'error',
          error: error.message,
          message: `Failed: ${error.message}`
        });
        writer.end();
      }
    } else if (!res.headersSent) {
      res.status(500).json({
        success: false,
        error: error.message
      });
    }
  }
});

export default router;